Disconnect Switch: Learn the Purpose, Cost, and Lead Time to Procure

Disconnect switch
Disconnect switch

Purpose of disconnect switch

  • Disconnect switches establish isolation points to enable equipment maintenance. They are installed on both sides of the circuit breaker, high-side of the transformer, and on the line exit.
Location of disconnect switches inside a substation
Location of disconnect switches inside a substation
  • Switches cannot and should not be used to interrupt load current or fault current. A switch operation takes place after the circuit is de-energized.
Disconnect Switch: Learn the Purpose, Cost, and Lead Time to Procure 1
Arcing shown here occurs during to capacitive charging current from long lines. When the switch is on a transformer, arcing occurs due to the magnetizing current.

Cost of disconnect switch

A switch can be designed in numerous ways – vertical break, center break, side break, double side break, pantograph, etc. View some of them here. The prices below reflect your typical vertical break configuration.

  • 15kV 600A/1200A disconnect switch with manual operator: ~$7,000
  • 35kV 1200A disconnect switch with manual operator: ~$7,000
  • 69kV 1200A disconnect switch with manual operator: ~$14,000
  • 138kV 2000A disconnect switch with motor operator: ~$20,000
  • 230kV 3000A disconnect switch with motor operator: ~$33,000
  • 345kV 3000A disconnect switch with motor operator: ~$66,000
  • 500kV 3000A disconnect switch with motor operator: ~$102,000
  • 765kV 3000A disconnect switch with motor operator: ~$150,000

Note: The cost includes the price of structural steel. For 138kV and above, the price of steel for high switch stand used (for conservative figures).

Lead time to procure disconnect switch

~22 weeks for a high voltage switch.

Information on cost and lead time is for your general knowledge only. Contact vendor with your equipment specifications for actual figures.

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Disconnect Switch: Learn the Purpose, Cost, and Lead Time to Procure 2

Substation Major Equipment

It’s only stupid-simple, let’s begin.

For which event should a surge arrester operate? Check all that apply.
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You are building an interconnect station, tying wind farm generation to the power grid. At the substation, the sources are tied through a tie-breaker. Which device would you install to make sure the sources are synchronized?
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A transformer develops an internal fault. Which device would you install on the transformer high-side to interrupt fault current?
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What’s the purpose of a conventional power transformer?
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In a distribution substation, the available ground-fault current on the low side of the step-down transformer is excessive, over-dutying the switching equipment. What is your cost-effective solution to reducing the fault current?
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Which combination of devices would you use to implement power line carrier?
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An industrial facility is plagued with voltage flicker (due to harmonics) and poor power factor at the service entrance. Which device would you install to fix both issues?
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Your score is

The average score is 40%

Aleen Mohammed

Aleen Mohammed

Registered Professional Engineer | MSEE
Skillset: Substation Design | Power System Studies | Arc Flash Study
DISCLAIMER: ALL VIEWS EXPRESSED IN THIS ARTICLE ARE MINE ALONE.

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